Gram quantities of glycerol 3-phosphate dehydrogenase can be obtained from chicken breast muscle by conventional protein purification methods or by affinity chromatography. The enzyme is a dimer of 74,000 molecular weight which can be readily crystallized. As part of a continuing study of the structure and metabolic function of glycerol 3-phosphate dehydrogenase we propose to sequence the enzyme. Peptides, generated by CNBr or trypsin cleavage will be isolated by gel permeation chromatography or by high pressure liquid chromatography. The isolated peptides will be coupled to a solid phase matrixa la Laursen and sequenced by Edman degradations. The amino acid sequence will be compared to that of other dehydrogenases and sugar phosphate metabolizing enzymes to determine homologies which in turn may provide information on the tertiary structure and evolution of glycerol 3-phosphate dehydrogenase.